//
//  KSCrypto.m
//  GO
//
//  Created by Kyle Sun on 05/09/2016.
//  Copyright © 2016 INMOTION. All rights reserved.
//

#import "KSCrypto.h"
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonCryptor.h>

#define gkey            @"7JgMcFUrYsrmOauu" //自行修改
#define gIv             @"Y3tGRVFXjFgoctsr" //自行修改

@implementation KSCrypto

+ (NSString *)md5Encrypt:(NSString *)string {
    if (string) {
        const char *cStr = [string UTF8String];
        
        unsigned char result[32];
        
        CC_MD5(cStr, (CC_LONG)strlen(cStr), result);
        
        return [NSString stringWithFormat:
                @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
                result[0], result[1], result[2], result[3],
                result[4], result[5], result[6], result[7],
                result[8], result[9], result[10], result[11],
                result[12], result[13], result[14], result[15]];
    }
    return nil;
}

+ (NSString *)aes128Encrypt:(NSString *)plainText {
    char keyPtr[kCCKeySizeAES128 + 1];
    memset(keyPtr, 0, sizeof(keyPtr));
    [gkey getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    
    char ivPtr[kCCBlockSizeAES128 + 1];
    memset(ivPtr, 0, sizeof(ivPtr));
    [gIv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];
    
    NSData *data = [plainText dataUsingEncoding:NSUTF8StringEncoding];
    NSUInteger dataLength = [data length];
    
    int diff = kCCKeySizeAES128 - (dataLength % kCCKeySizeAES128);
    int newSize = 0;
    
    if (diff > 0) {
        newSize = (int)(dataLength + diff);
    }
    
    char dataPtr[newSize];
    memcpy(dataPtr, [data bytes], [data length]);
    for (int i = 0; i < diff; i++) {
        dataPtr[i + dataLength] = 0x00;
    }
    
    size_t bufferSize = newSize + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    memset(buffer, 0, bufferSize);
    
    size_t numBytesCrypted = 0;
    
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
                                          kCCAlgorithmAES128,
                                          0x0000,               //No padding
                                          keyPtr,
                                          kCCKeySizeAES128,
                                          ivPtr,
                                          dataPtr,
                                          sizeof(dataPtr),
                                          buffer,
                                          bufferSize,
                                          &numBytesCrypted);
    
    if (cryptStatus == kCCSuccess) {
        NSData *resultData = [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted];
        return [resultData base64EncodedStringWithOptions:kNilOptions];
    }
    free(buffer);
    return nil;
}

+ (NSString *)aes128Decrypt:(NSString *)encryptText {
    char keyPtr[kCCKeySizeAES128 + 1];
    memset(keyPtr, 0, sizeof(keyPtr));
    [gkey getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    
    char ivPtr[kCCBlockSizeAES128 + 1];
    memset(ivPtr, 0, sizeof(ivPtr));
    [gIv getCString:ivPtr maxLength:sizeof(ivPtr) encoding:NSUTF8StringEncoding];
    
    NSData *data = [[NSData alloc] initWithBase64EncodedData:[encryptText dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions];
    NSUInteger dataLength = [data length];
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    
    size_t numBytesCrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
                                          kCCAlgorithmAES128,
                                          0x0000,
                                          keyPtr,
                                          kCCBlockSizeAES128,
                                          ivPtr,
                                          [data bytes],
                                          dataLength,
                                          buffer,
                                          bufferSize,
                                          &numBytesCrypted);
    if (cryptStatus == kCCSuccess) {
        NSData *resultData = [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted];
        return [[NSString alloc] initWithData:resultData encoding:NSUTF8StringEncoding];
    }
    free(buffer);
    return nil;
}

@end
